1. Field of the Invention
This invention relates to telephone systems and more particularly to a system which utilizes the combination of one or more unconventional minimum component handsets and one or more master units to provide at least standard telephone service.
2. Description of the Prior Art
Since conception, the telephone instrument has provided a basic means of conducting voice communications between two or more parties. The generic instrument serves the functions of converting destination information into electrical signals for call routing (dialing), alerting the user to incoming calls (ringing) and providing voice communications by converting electrical into acoustical signals and vice versa.
As time has passed, the role of the telephone instrument has taken on new dimensions, many of which have resulted in added circuit complexity. This is especially true when the instrument is used as an integral part of a telephone system but also analog to digital electrical signal conversion.
Today, there are numerous small telephone systems in the form of private automatic branch exchanges (PABX) and key telephone sysems (KTS) that offer enhanced servies to their users. These small systems generally comprise an electronics package sometimes referred to as the common equipment to which all of the telephones in the system have access. A feature common to all of these systems is the use therein of telephone instruments which are no less complex than the conventional standard instrument. A conventional standard tone system telephone includes a transmitter, a receiver, a switch hook, a bell ringer, a tone keypad with tone generating means and a hybrid circuit. In many cases, these systems also involve the use of instruments which are substantially more complex than the conventional standard instruments. These instruments include additional elements generally in the form of electronics to provide functions such as call forwarding, repertory dialing, etc.
It was then recognized that a system serving a multiplicity of telephones could be provided wherein functions common to all of the systems' telephone instruments such as ringing and dialing could be placed in a master unit to which all of the instruments have access. This placement of the common functions in a master unit then allows the conventional standard telephone to be replaced with a handset which is substantially less complex and costly than even the conventional instrument. This new, less costly and relatively simple instrument will be referred to hereinafter as the "unconventional telephone". It was also recognized that such a system could provide a multitude of enhanced subscriber services (some of which are described above) without the necessity of using even more complex instruments. A simple expansion of the capability of the master unit will allow one or more of those enhanced services to be provided to all of the systems inconventional telephones.
It was further recognized that such a system could be configured in a form useful for single line applications or in a form similar to present key telephone systems. It was even further recognized that the system for single line applications could be designed in a manner such that those subscribers having station wiring with at least four conductors could use their already in place conventional telephones in conjunction with the system of the present invention. This feature allows such a subscriber to have access to enhanced services without having to do anything more than connect the system of the present invention to his station wiring.